Floating hotkey window

This is based on an old patch of yours and fixes https://code.google.com/p/iterm2/issues/detail?id=1570

The weird behauvior you describe is nowhere to be seen, at least not in yosemite. I added some code which sucessfully detected whether the hotkeywindow was over an fullscreen app, but when I couldn't figure out how to move the window up in this case, as my origin.y was seemingly reset everytime. Maybe you know where that's coming from.
Why remove this? It was useful for preventing notifications from a terminal window occluded by another terminal window.